There are conventionally well known linear motion guide units of the type hereinafter referred to as “finite linear motion guide unit” because of their construction where rolling elements are allowed to roll over only a definite travel instead of rolling through a recirculation circuit. Most of the finite linear motion guide units have retainers or cages to space rolling elements from each other, which are allowed to run through a race provided between a guide rail and a slider. With the finite linear motion guide units of the sort described earlier, moreover, stopper plugs are usually provided at forward and aft ends of the guide rail, one to each end, to keep the retainer against from escape out of the associated guide rail. In terms of fastening construction of the stopper plugs to their associated ends of the guide rail, there has been already known the stopper construction making it possible to secure the stopper plug to the associated end of the guide rail by using just one fastener screw in a way kept against turning around its own axis, thereby rendering the fastening of the stopper plug to the guide rail simpler in construction.
The finite linear motion guide unit of the sort as constructed as stated earlier is disclosed in, for example Japanese Patent Laid-Open No. 2000-27860. The prior finite linear motion guide unit, as shown in FIG.18, is made up of an elongated guide rail 52 having widthwise opposite sides on which are made lengthwise raceway grooves 54, one to each side, a slider 51 made to fit over and conform to the guide rail 52 and have raceway grooves 53 in opposition to the raceway grooves 54 on the guide rail 52, and a retainer 59 made with more than one pocket 62 to accommodate therein more than one rolling element 55, one to each pocket, which is allowed to roll through a race defined between the confronting guide rail 52 and slider 51. A stopper plug 57 is secured to any one end 61 of the guide rail 52 with using just one screw 63. The stopper plug 57 is so made as to allow the slider 51 passing over there without running into any interference with an end plate 56 mounted with screws 58 to any one end of the slider 51, which moves relatively to the guide rail 52. The stopper plug 57, moreover, has projections 60 extending sidewise out of widthwise corners thereof so as to come into engagement with the retainer 59 thereby keeping the retainer 59 against falling away out of the linear motion guide unit. The projections 60 are angled slightly together with their associated corners of the stopper plug 57 towards the sides of the guide rail 52 to come into engagement with the sidewise edges on the end face of the guide rail 52, keeping the stopper plug 57 against turning on a lengthwise direction of the guide rail 52.
With the prior finite linear motion guide unit constructed as stated earlier, the stopper plug 57 has sidewise projections 60, which lean back slightly towards the associated end 61 of the guide rail 52. This slightly askew construction of the projection 60 works well enough to keep the stopper plug 57 against turning or angular shift on the lengthwise direction of the guide rail 52, even with just one fastening screw 58. The stopper plug 57, moreover, is made to have restoration from the deformation caused by tightening of the fastening screw 58, thereby preventing loosening or unscrewing of the fastening screw 58. The conventional finite linear motion guide unit of the construction as stated just earlier, nevertheless, has needed several more chores to fit accurately the tiny stopper plug 57 onto the end face of the guide rail 52 to meet a growing demand for shrinking the linear motion guide unit down. Moreover, accurately bending the stopper plug 57 to provide the sidewise projections 60 has been proved to be difficult and complex.